The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/fs/nfsclient/nfs_clbio.c

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    1 /*-
    2  * Copyright (c) 1989, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This code is derived from software contributed to Berkeley by
    6  * Rick Macklem at The University of Guelph.
    7  *
    8  * Redistribution and use in source and binary forms, with or without
    9  * modification, are permitted provided that the following conditions
   10  * are met:
   11  * 1. Redistributions of source code must retain the above copyright
   12  *    notice, this list of conditions and the following disclaimer.
   13  * 2. Redistributions in binary form must reproduce the above copyright
   14  *    notice, this list of conditions and the following disclaimer in the
   15  *    documentation and/or other materials provided with the distribution.
   16  * 4. Neither the name of the University nor the names of its contributors
   17  *    may be used to endorse or promote products derived from this software
   18  *    without specific prior written permission.
   19  *
   20  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   21  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   22  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   23  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   24  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   25  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   26  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   27  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   28  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   29  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   30  * SUCH DAMAGE.
   31  *
   32  *      @(#)nfs_bio.c   8.9 (Berkeley) 3/30/95
   33  */
   34 
   35 #include <sys/cdefs.h>
   36 __FBSDID("$FreeBSD: releng/9.1/sys/fs/nfsclient/nfs_clbio.c 236446 2012-06-02 11:44:50Z kib $");
   37 
   38 #include "opt_kdtrace.h"
   39 
   40 #include <sys/param.h>
   41 #include <sys/systm.h>
   42 #include <sys/bio.h>
   43 #include <sys/buf.h>
   44 #include <sys/kernel.h>
   45 #include <sys/mount.h>
   46 #include <sys/vmmeter.h>
   47 #include <sys/vnode.h>
   48 
   49 #include <vm/vm.h>
   50 #include <vm/vm_extern.h>
   51 #include <vm/vm_page.h>
   52 #include <vm/vm_object.h>
   53 #include <vm/vm_pager.h>
   54 #include <vm/vnode_pager.h>
   55 
   56 #include <fs/nfs/nfsport.h>
   57 #include <fs/nfsclient/nfsmount.h>
   58 #include <fs/nfsclient/nfs.h>
   59 #include <fs/nfsclient/nfsnode.h>
   60 #include <fs/nfsclient/nfs_kdtrace.h>
   61 
   62 extern int newnfs_directio_allow_mmap;
   63 extern struct nfsstats newnfsstats;
   64 extern struct mtx ncl_iod_mutex;
   65 extern int ncl_numasync;
   66 extern enum nfsiod_state ncl_iodwant[NFS_MAXASYNCDAEMON];
   67 extern struct nfsmount *ncl_iodmount[NFS_MAXASYNCDAEMON];
   68 extern int newnfs_directio_enable;
   69 extern int nfs_keep_dirty_on_error;
   70 
   71 int ncl_pbuf_freecnt = -1;      /* start out unlimited */
   72 
   73 static struct buf *nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size,
   74     struct thread *td);
   75 static int nfs_directio_write(struct vnode *vp, struct uio *uiop, 
   76     struct ucred *cred, int ioflag);
   77 
   78 /*
   79  * Vnode op for VM getpages.
   80  */
   81 int
   82 ncl_getpages(struct vop_getpages_args *ap)
   83 {
   84         int i, error, nextoff, size, toff, count, npages;
   85         struct uio uio;
   86         struct iovec iov;
   87         vm_offset_t kva;
   88         struct buf *bp;
   89         struct vnode *vp;
   90         struct thread *td;
   91         struct ucred *cred;
   92         struct nfsmount *nmp;
   93         vm_object_t object;
   94         vm_page_t *pages;
   95         struct nfsnode *np;
   96 
   97         vp = ap->a_vp;
   98         np = VTONFS(vp);
   99         td = curthread;                         /* XXX */
  100         cred = curthread->td_ucred;             /* XXX */
  101         nmp = VFSTONFS(vp->v_mount);
  102         pages = ap->a_m;
  103         count = ap->a_count;
  104 
  105         if ((object = vp->v_object) == NULL) {
  106                 ncl_printf("nfs_getpages: called with non-merged cache vnode??\n");
  107                 return (VM_PAGER_ERROR);
  108         }
  109 
  110         if (newnfs_directio_enable && !newnfs_directio_allow_mmap) {
  111                 mtx_lock(&np->n_mtx);
  112                 if ((np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  113                         mtx_unlock(&np->n_mtx);
  114                         ncl_printf("nfs_getpages: called on non-cacheable vnode??\n");
  115                         return (VM_PAGER_ERROR);
  116                 } else
  117                         mtx_unlock(&np->n_mtx);
  118         }
  119 
  120         mtx_lock(&nmp->nm_mtx);
  121         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  122             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {  
  123                 mtx_unlock(&nmp->nm_mtx);
  124                 /* We'll never get here for v4, because we always have fsinfo */
  125                 (void)ncl_fsinfo(nmp, vp, cred, td);
  126         } else
  127                 mtx_unlock(&nmp->nm_mtx);
  128 
  129         npages = btoc(count);
  130 
  131         /*
  132          * If the requested page is partially valid, just return it and
  133          * allow the pager to zero-out the blanks.  Partially valid pages
  134          * can only occur at the file EOF.
  135          */
  136         VM_OBJECT_LOCK(object);
  137         if (pages[ap->a_reqpage]->valid != 0) {
  138                 for (i = 0; i < npages; ++i) {
  139                         if (i != ap->a_reqpage) {
  140                                 vm_page_lock(pages[i]);
  141                                 vm_page_free(pages[i]);
  142                                 vm_page_unlock(pages[i]);
  143                         }
  144                 }
  145                 VM_OBJECT_UNLOCK(object);
  146                 return (0);
  147         }
  148         VM_OBJECT_UNLOCK(object);
  149 
  150         /*
  151          * We use only the kva address for the buffer, but this is extremely
  152          * convienient and fast.
  153          */
  154         bp = getpbuf(&ncl_pbuf_freecnt);
  155 
  156         kva = (vm_offset_t) bp->b_data;
  157         pmap_qenter(kva, pages, npages);
  158         PCPU_INC(cnt.v_vnodein);
  159         PCPU_ADD(cnt.v_vnodepgsin, npages);
  160 
  161         iov.iov_base = (caddr_t) kva;
  162         iov.iov_len = count;
  163         uio.uio_iov = &iov;
  164         uio.uio_iovcnt = 1;
  165         uio.uio_offset = IDX_TO_OFF(pages[0]->pindex);
  166         uio.uio_resid = count;
  167         uio.uio_segflg = UIO_SYSSPACE;
  168         uio.uio_rw = UIO_READ;
  169         uio.uio_td = td;
  170 
  171         error = ncl_readrpc(vp, &uio, cred);
  172         pmap_qremove(kva, npages);
  173 
  174         relpbuf(bp, &ncl_pbuf_freecnt);
  175 
  176         if (error && (uio.uio_resid == count)) {
  177                 ncl_printf("nfs_getpages: error %d\n", error);
  178                 VM_OBJECT_LOCK(object);
  179                 for (i = 0; i < npages; ++i) {
  180                         if (i != ap->a_reqpage) {
  181                                 vm_page_lock(pages[i]);
  182                                 vm_page_free(pages[i]);
  183                                 vm_page_unlock(pages[i]);
  184                         }
  185                 }
  186                 VM_OBJECT_UNLOCK(object);
  187                 return (VM_PAGER_ERROR);
  188         }
  189 
  190         /*
  191          * Calculate the number of bytes read and validate only that number
  192          * of bytes.  Note that due to pending writes, size may be 0.  This
  193          * does not mean that the remaining data is invalid!
  194          */
  195 
  196         size = count - uio.uio_resid;
  197         VM_OBJECT_LOCK(object);
  198         for (i = 0, toff = 0; i < npages; i++, toff = nextoff) {
  199                 vm_page_t m;
  200                 nextoff = toff + PAGE_SIZE;
  201                 m = pages[i];
  202 
  203                 if (nextoff <= size) {
  204                         /*
  205                          * Read operation filled an entire page
  206                          */
  207                         m->valid = VM_PAGE_BITS_ALL;
  208                         KASSERT(m->dirty == 0,
  209                             ("nfs_getpages: page %p is dirty", m));
  210                 } else if (size > toff) {
  211                         /*
  212                          * Read operation filled a partial page.
  213                          */
  214                         m->valid = 0;
  215                         vm_page_set_valid(m, 0, size - toff);
  216                         KASSERT(m->dirty == 0,
  217                             ("nfs_getpages: page %p is dirty", m));
  218                 } else {
  219                         /*
  220                          * Read operation was short.  If no error occured
  221                          * we may have hit a zero-fill section.   We simply
  222                          * leave valid set to 0.
  223                          */
  224                         ;
  225                 }
  226                 if (i != ap->a_reqpage) {
  227                         /*
  228                          * Whether or not to leave the page activated is up in
  229                          * the air, but we should put the page on a page queue
  230                          * somewhere (it already is in the object).  Result:
  231                          * It appears that emperical results show that
  232                          * deactivating pages is best.
  233                          */
  234 
  235                         /*
  236                          * Just in case someone was asking for this page we
  237                          * now tell them that it is ok to use.
  238                          */
  239                         if (!error) {
  240                                 if (m->oflags & VPO_WANTED) {
  241                                         vm_page_lock(m);
  242                                         vm_page_activate(m);
  243                                         vm_page_unlock(m);
  244                                 } else {
  245                                         vm_page_lock(m);
  246                                         vm_page_deactivate(m);
  247                                         vm_page_unlock(m);
  248                                 }
  249                                 vm_page_wakeup(m);
  250                         } else {
  251                                 vm_page_lock(m);
  252                                 vm_page_free(m);
  253                                 vm_page_unlock(m);
  254                         }
  255                 }
  256         }
  257         VM_OBJECT_UNLOCK(object);
  258         return (0);
  259 }
  260 
  261 /*
  262  * Vnode op for VM putpages.
  263  */
  264 int
  265 ncl_putpages(struct vop_putpages_args *ap)
  266 {
  267         struct uio uio;
  268         struct iovec iov;
  269         vm_offset_t kva;
  270         struct buf *bp;
  271         int iomode, must_commit, i, error, npages, count;
  272         off_t offset;
  273         int *rtvals;
  274         struct vnode *vp;
  275         struct thread *td;
  276         struct ucred *cred;
  277         struct nfsmount *nmp;
  278         struct nfsnode *np;
  279         vm_page_t *pages;
  280 
  281         vp = ap->a_vp;
  282         np = VTONFS(vp);
  283         td = curthread;                         /* XXX */
  284         /* Set the cred to n_writecred for the write rpcs. */
  285         if (np->n_writecred != NULL)
  286                 cred = crhold(np->n_writecred);
  287         else
  288                 cred = crhold(curthread->td_ucred);     /* XXX */
  289         nmp = VFSTONFS(vp->v_mount);
  290         pages = ap->a_m;
  291         count = ap->a_count;
  292         rtvals = ap->a_rtvals;
  293         npages = btoc(count);
  294         offset = IDX_TO_OFF(pages[0]->pindex);
  295         
  296         mtx_lock(&nmp->nm_mtx);
  297         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  298             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  299                 mtx_unlock(&nmp->nm_mtx);
  300                 (void)ncl_fsinfo(nmp, vp, cred, td);
  301         } else
  302                 mtx_unlock(&nmp->nm_mtx);
  303 
  304         mtx_lock(&np->n_mtx);
  305         if (newnfs_directio_enable && !newnfs_directio_allow_mmap && 
  306             (np->n_flag & NNONCACHE) && (vp->v_type == VREG)) {
  307                 mtx_unlock(&np->n_mtx);         
  308                 ncl_printf("ncl_putpages: called on noncache-able vnode??\n");
  309                 mtx_lock(&np->n_mtx);
  310         }
  311 
  312         for (i = 0; i < npages; i++)
  313                 rtvals[i] = VM_PAGER_ERROR;
  314 
  315         /*
  316          * When putting pages, do not extend file past EOF.
  317          */
  318         if (offset + count > np->n_size) {
  319                 count = np->n_size - offset;
  320                 if (count < 0)
  321                         count = 0;
  322         }
  323         mtx_unlock(&np->n_mtx);
  324 
  325         /*
  326          * We use only the kva address for the buffer, but this is extremely
  327          * convienient and fast.
  328          */
  329         bp = getpbuf(&ncl_pbuf_freecnt);
  330 
  331         kva = (vm_offset_t) bp->b_data;
  332         pmap_qenter(kva, pages, npages);
  333         PCPU_INC(cnt.v_vnodeout);
  334         PCPU_ADD(cnt.v_vnodepgsout, count);
  335 
  336         iov.iov_base = (caddr_t) kva;
  337         iov.iov_len = count;
  338         uio.uio_iov = &iov;
  339         uio.uio_iovcnt = 1;
  340         uio.uio_offset = offset;
  341         uio.uio_resid = count;
  342         uio.uio_segflg = UIO_SYSSPACE;
  343         uio.uio_rw = UIO_WRITE;
  344         uio.uio_td = td;
  345 
  346         if ((ap->a_sync & VM_PAGER_PUT_SYNC) == 0)
  347             iomode = NFSWRITE_UNSTABLE;
  348         else
  349             iomode = NFSWRITE_FILESYNC;
  350 
  351         error = ncl_writerpc(vp, &uio, cred, &iomode, &must_commit, 0);
  352         crfree(cred);
  353 
  354         pmap_qremove(kva, npages);
  355         relpbuf(bp, &ncl_pbuf_freecnt);
  356 
  357         if (error == 0 || !nfs_keep_dirty_on_error) {
  358                 vnode_pager_undirty_pages(pages, rtvals, count - uio.uio_resid);
  359                 if (must_commit)
  360                         ncl_clearcommit(vp->v_mount);
  361         }
  362         return rtvals[0];
  363 }
  364 
  365 /*
  366  * For nfs, cache consistency can only be maintained approximately.
  367  * Although RFC1094 does not specify the criteria, the following is
  368  * believed to be compatible with the reference port.
  369  * For nfs:
  370  * If the file's modify time on the server has changed since the
  371  * last read rpc or you have written to the file,
  372  * you may have lost data cache consistency with the
  373  * server, so flush all of the file's data out of the cache.
  374  * Then force a getattr rpc to ensure that you have up to date
  375  * attributes.
  376  * NB: This implies that cache data can be read when up to
  377  * NFS_ATTRTIMEO seconds out of date. If you find that you need current
  378  * attributes this could be forced by setting n_attrstamp to 0 before
  379  * the VOP_GETATTR() call.
  380  */
  381 static inline int
  382 nfs_bioread_check_cons(struct vnode *vp, struct thread *td, struct ucred *cred)
  383 {
  384         int error = 0;
  385         struct vattr vattr;
  386         struct nfsnode *np = VTONFS(vp);
  387         int old_lock;
  388         
  389         /*
  390          * Grab the exclusive lock before checking whether the cache is
  391          * consistent.
  392          * XXX - We can make this cheaper later (by acquiring cheaper locks).
  393          * But for now, this suffices.
  394          */
  395         old_lock = ncl_upgrade_vnlock(vp);
  396         if (vp->v_iflag & VI_DOOMED) {
  397                 ncl_downgrade_vnlock(vp, old_lock);
  398                 return (EBADF);
  399         }
  400 
  401         mtx_lock(&np->n_mtx);
  402         if (np->n_flag & NMODIFIED) {
  403                 mtx_unlock(&np->n_mtx);
  404                 if (vp->v_type != VREG) {
  405                         if (vp->v_type != VDIR)
  406                                 panic("nfs: bioread, not dir");
  407                         ncl_invaldir(vp);
  408                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  409                         if (error)
  410                                 goto out;
  411                 }
  412                 np->n_attrstamp = 0;
  413                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  414                 error = VOP_GETATTR(vp, &vattr, cred);
  415                 if (error)
  416                         goto out;
  417                 mtx_lock(&np->n_mtx);
  418                 np->n_mtime = vattr.va_mtime;
  419                 mtx_unlock(&np->n_mtx);
  420         } else {
  421                 mtx_unlock(&np->n_mtx);
  422                 error = VOP_GETATTR(vp, &vattr, cred);
  423                 if (error)
  424                         return (error);
  425                 mtx_lock(&np->n_mtx);
  426                 if ((np->n_flag & NSIZECHANGED)
  427                     || (NFS_TIMESPEC_COMPARE(&np->n_mtime, &vattr.va_mtime))) {
  428                         mtx_unlock(&np->n_mtx);
  429                         if (vp->v_type == VDIR)
  430                                 ncl_invaldir(vp);
  431                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  432                         if (error)
  433                                 goto out;
  434                         mtx_lock(&np->n_mtx);
  435                         np->n_mtime = vattr.va_mtime;
  436                         np->n_flag &= ~NSIZECHANGED;
  437                 }
  438                 mtx_unlock(&np->n_mtx);
  439         }
  440 out:    
  441         ncl_downgrade_vnlock(vp, old_lock);
  442         return error;
  443 }
  444 
  445 /*
  446  * Vnode op for read using bio
  447  */
  448 int
  449 ncl_bioread(struct vnode *vp, struct uio *uio, int ioflag, struct ucred *cred)
  450 {
  451         struct nfsnode *np = VTONFS(vp);
  452         int biosize, i;
  453         struct buf *bp, *rabp;
  454         struct thread *td;
  455         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  456         daddr_t lbn, rabn;
  457         int bcount;
  458         int seqcount;
  459         int nra, error = 0, n = 0, on = 0;
  460         off_t tmp_off;
  461 
  462         KASSERT(uio->uio_rw == UIO_READ, ("ncl_read mode"));
  463         if (uio->uio_resid == 0)
  464                 return (0);
  465         if (uio->uio_offset < 0)        /* XXX VDIR cookies can be negative */
  466                 return (EINVAL);
  467         td = uio->uio_td;
  468 
  469         mtx_lock(&nmp->nm_mtx);
  470         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  471             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  472                 mtx_unlock(&nmp->nm_mtx);
  473                 (void)ncl_fsinfo(nmp, vp, cred, td);
  474                 mtx_lock(&nmp->nm_mtx);
  475         }
  476         if (nmp->nm_rsize == 0 || nmp->nm_readdirsize == 0)
  477                 (void) newnfs_iosize(nmp);
  478 
  479         tmp_off = uio->uio_offset + uio->uio_resid;
  480         if (vp->v_type != VDIR &&
  481             (tmp_off > nmp->nm_maxfilesize || tmp_off < uio->uio_offset)) {
  482                 mtx_unlock(&nmp->nm_mtx);               
  483                 return (EFBIG);
  484         }
  485         mtx_unlock(&nmp->nm_mtx);               
  486 
  487         if (newnfs_directio_enable && (ioflag & IO_DIRECT) && (vp->v_type == VREG))
  488                 /* No caching/ no readaheads. Just read data into the user buffer */
  489                 return ncl_readrpc(vp, uio, cred);
  490 
  491         biosize = vp->v_bufobj.bo_bsize;
  492         seqcount = (int)((off_t)(ioflag >> IO_SEQSHIFT) * biosize / BKVASIZE);
  493         
  494         error = nfs_bioread_check_cons(vp, td, cred);
  495         if (error)
  496                 return error;
  497 
  498         do {
  499             u_quad_t nsize;
  500                         
  501             mtx_lock(&np->n_mtx);
  502             nsize = np->n_size;
  503             mtx_unlock(&np->n_mtx);                 
  504 
  505             switch (vp->v_type) {
  506             case VREG:
  507                 NFSINCRGLOBAL(newnfsstats.biocache_reads);
  508                 lbn = uio->uio_offset / biosize;
  509                 on = uio->uio_offset & (biosize - 1);
  510 
  511                 /*
  512                  * Start the read ahead(s), as required.
  513                  */
  514                 if (nmp->nm_readahead > 0) {
  515                     for (nra = 0; nra < nmp->nm_readahead && nra < seqcount &&
  516                         (off_t)(lbn + 1 + nra) * biosize < nsize; nra++) {
  517                         rabn = lbn + 1 + nra;
  518                         if (incore(&vp->v_bufobj, rabn) == NULL) {
  519                             rabp = nfs_getcacheblk(vp, rabn, biosize, td);
  520                             if (!rabp) {
  521                                 error = newnfs_sigintr(nmp, td);
  522                                 return (error ? error : EINTR);
  523                             }
  524                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  525                                 rabp->b_flags |= B_ASYNC;
  526                                 rabp->b_iocmd = BIO_READ;
  527                                 vfs_busy_pages(rabp, 0);
  528                                 if (ncl_asyncio(nmp, rabp, cred, td)) {
  529                                     rabp->b_flags |= B_INVAL;
  530                                     rabp->b_ioflags |= BIO_ERROR;
  531                                     vfs_unbusy_pages(rabp);
  532                                     brelse(rabp);
  533                                     break;
  534                                 }
  535                             } else {
  536                                 brelse(rabp);
  537                             }
  538                         }
  539                     }
  540                 }
  541 
  542                 /* Note that bcount is *not* DEV_BSIZE aligned. */
  543                 bcount = biosize;
  544                 if ((off_t)lbn * biosize >= nsize) {
  545                         bcount = 0;
  546                 } else if ((off_t)(lbn + 1) * biosize > nsize) {
  547                         bcount = nsize - (off_t)lbn * biosize;
  548                 }
  549                 bp = nfs_getcacheblk(vp, lbn, bcount, td);
  550 
  551                 if (!bp) {
  552                         error = newnfs_sigintr(nmp, td);
  553                         return (error ? error : EINTR);
  554                 }
  555 
  556                 /*
  557                  * If B_CACHE is not set, we must issue the read.  If this
  558                  * fails, we return an error.
  559                  */
  560 
  561                 if ((bp->b_flags & B_CACHE) == 0) {
  562                     bp->b_iocmd = BIO_READ;
  563                     vfs_busy_pages(bp, 0);
  564                     error = ncl_doio(vp, bp, cred, td, 0);
  565                     if (error) {
  566                         brelse(bp);
  567                         return (error);
  568                     }
  569                 }
  570 
  571                 /*
  572                  * on is the offset into the current bp.  Figure out how many
  573                  * bytes we can copy out of the bp.  Note that bcount is
  574                  * NOT DEV_BSIZE aligned.
  575                  *
  576                  * Then figure out how many bytes we can copy into the uio.
  577                  */
  578 
  579                 n = 0;
  580                 if (on < bcount)
  581                         n = MIN((unsigned)(bcount - on), uio->uio_resid);
  582                 break;
  583             case VLNK:
  584                 NFSINCRGLOBAL(newnfsstats.biocache_readlinks);
  585                 bp = nfs_getcacheblk(vp, (daddr_t)0, NFS_MAXPATHLEN, td);
  586                 if (!bp) {
  587                         error = newnfs_sigintr(nmp, td);
  588                         return (error ? error : EINTR);
  589                 }
  590                 if ((bp->b_flags & B_CACHE) == 0) {
  591                     bp->b_iocmd = BIO_READ;
  592                     vfs_busy_pages(bp, 0);
  593                     error = ncl_doio(vp, bp, cred, td, 0);
  594                     if (error) {
  595                         bp->b_ioflags |= BIO_ERROR;
  596                         brelse(bp);
  597                         return (error);
  598                     }
  599                 }
  600                 n = MIN(uio->uio_resid, NFS_MAXPATHLEN - bp->b_resid);
  601                 on = 0;
  602                 break;
  603             case VDIR:
  604                 NFSINCRGLOBAL(newnfsstats.biocache_readdirs);
  605                 if (np->n_direofoffset
  606                     && uio->uio_offset >= np->n_direofoffset) {
  607                     return (0);
  608                 }
  609                 lbn = (uoff_t)uio->uio_offset / NFS_DIRBLKSIZ;
  610                 on = uio->uio_offset & (NFS_DIRBLKSIZ - 1);
  611                 bp = nfs_getcacheblk(vp, lbn, NFS_DIRBLKSIZ, td);
  612                 if (!bp) {
  613                     error = newnfs_sigintr(nmp, td);
  614                     return (error ? error : EINTR);
  615                 }
  616                 if ((bp->b_flags & B_CACHE) == 0) {
  617                     bp->b_iocmd = BIO_READ;
  618                     vfs_busy_pages(bp, 0);
  619                     error = ncl_doio(vp, bp, cred, td, 0);
  620                     if (error) {
  621                             brelse(bp);
  622                     }
  623                     while (error == NFSERR_BAD_COOKIE) {
  624                         ncl_invaldir(vp);
  625                         error = ncl_vinvalbuf(vp, 0, td, 1);
  626                         /*
  627                          * Yuck! The directory has been modified on the
  628                          * server. The only way to get the block is by
  629                          * reading from the beginning to get all the
  630                          * offset cookies.
  631                          *
  632                          * Leave the last bp intact unless there is an error.
  633                          * Loop back up to the while if the error is another
  634                          * NFSERR_BAD_COOKIE (double yuch!).
  635                          */
  636                         for (i = 0; i <= lbn && !error; i++) {
  637                             if (np->n_direofoffset
  638                                 && (i * NFS_DIRBLKSIZ) >= np->n_direofoffset)
  639                                     return (0);
  640                             bp = nfs_getcacheblk(vp, i, NFS_DIRBLKSIZ, td);
  641                             if (!bp) {
  642                                 error = newnfs_sigintr(nmp, td);
  643                                 return (error ? error : EINTR);
  644                             }
  645                             if ((bp->b_flags & B_CACHE) == 0) {
  646                                     bp->b_iocmd = BIO_READ;
  647                                     vfs_busy_pages(bp, 0);
  648                                     error = ncl_doio(vp, bp, cred, td, 0);
  649                                     /*
  650                                      * no error + B_INVAL == directory EOF,
  651                                      * use the block.
  652                                      */
  653                                     if (error == 0 && (bp->b_flags & B_INVAL))
  654                                             break;
  655                             }
  656                             /*
  657                              * An error will throw away the block and the
  658                              * for loop will break out.  If no error and this
  659                              * is not the block we want, we throw away the
  660                              * block and go for the next one via the for loop.
  661                              */
  662                             if (error || i < lbn)
  663                                     brelse(bp);
  664                         }
  665                     }
  666                     /*
  667                      * The above while is repeated if we hit another cookie
  668                      * error.  If we hit an error and it wasn't a cookie error,
  669                      * we give up.
  670                      */
  671                     if (error)
  672                             return (error);
  673                 }
  674 
  675                 /*
  676                  * If not eof and read aheads are enabled, start one.
  677                  * (You need the current block first, so that you have the
  678                  *  directory offset cookie of the next block.)
  679                  */
  680                 if (nmp->nm_readahead > 0 &&
  681                     (bp->b_flags & B_INVAL) == 0 &&
  682                     (np->n_direofoffset == 0 ||
  683                     (lbn + 1) * NFS_DIRBLKSIZ < np->n_direofoffset) &&
  684                     incore(&vp->v_bufobj, lbn + 1) == NULL) {
  685                         rabp = nfs_getcacheblk(vp, lbn + 1, NFS_DIRBLKSIZ, td);
  686                         if (rabp) {
  687                             if ((rabp->b_flags & (B_CACHE|B_DELWRI)) == 0) {
  688                                 rabp->b_flags |= B_ASYNC;
  689                                 rabp->b_iocmd = BIO_READ;
  690                                 vfs_busy_pages(rabp, 0);
  691                                 if (ncl_asyncio(nmp, rabp, cred, td)) {
  692                                     rabp->b_flags |= B_INVAL;
  693                                     rabp->b_ioflags |= BIO_ERROR;
  694                                     vfs_unbusy_pages(rabp);
  695                                     brelse(rabp);
  696                                 }
  697                             } else {
  698                                 brelse(rabp);
  699                             }
  700                         }
  701                 }
  702                 /*
  703                  * Unlike VREG files, whos buffer size ( bp->b_bcount ) is
  704                  * chopped for the EOF condition, we cannot tell how large
  705                  * NFS directories are going to be until we hit EOF.  So
  706                  * an NFS directory buffer is *not* chopped to its EOF.  Now,
  707                  * it just so happens that b_resid will effectively chop it
  708                  * to EOF.  *BUT* this information is lost if the buffer goes
  709                  * away and is reconstituted into a B_CACHE state ( due to
  710                  * being VMIO ) later.  So we keep track of the directory eof
  711                  * in np->n_direofoffset and chop it off as an extra step
  712                  * right here.
  713                  */
  714                 n = lmin(uio->uio_resid, NFS_DIRBLKSIZ - bp->b_resid - on);
  715                 if (np->n_direofoffset && n > np->n_direofoffset - uio->uio_offset)
  716                         n = np->n_direofoffset - uio->uio_offset;
  717                 break;
  718             default:
  719                 ncl_printf(" ncl_bioread: type %x unexpected\n", vp->v_type);
  720                 bp = NULL;
  721                 break;
  722             };
  723 
  724             if (n > 0) {
  725                     error = uiomove(bp->b_data + on, (int)n, uio);
  726             }
  727             if (vp->v_type == VLNK)
  728                 n = 0;
  729             if (bp != NULL)
  730                 brelse(bp);
  731         } while (error == 0 && uio->uio_resid > 0 && n > 0);
  732         return (error);
  733 }
  734 
  735 /*
  736  * The NFS write path cannot handle iovecs with len > 1. So we need to 
  737  * break up iovecs accordingly (restricting them to wsize).
  738  * For the SYNC case, we can do this with 1 copy (user buffer -> mbuf). 
  739  * For the ASYNC case, 2 copies are needed. The first a copy from the 
  740  * user buffer to a staging buffer and then a second copy from the staging
  741  * buffer to mbufs. This can be optimized by copying from the user buffer
  742  * directly into mbufs and passing the chain down, but that requires a 
  743  * fair amount of re-working of the relevant codepaths (and can be done
  744  * later).
  745  */
  746 static int
  747 nfs_directio_write(vp, uiop, cred, ioflag)
  748         struct vnode *vp;
  749         struct uio *uiop;
  750         struct ucred *cred;
  751         int ioflag;
  752 {
  753         int error;
  754         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  755         struct thread *td = uiop->uio_td;
  756         int size;
  757         int wsize;
  758         
  759         mtx_lock(&nmp->nm_mtx);
  760         wsize = nmp->nm_wsize;
  761         mtx_unlock(&nmp->nm_mtx);
  762         if (ioflag & IO_SYNC) {
  763                 int iomode, must_commit;
  764                 struct uio uio;
  765                 struct iovec iov;
  766 do_sync:
  767                 while (uiop->uio_resid > 0) {
  768                         size = MIN(uiop->uio_resid, wsize);
  769                         size = MIN(uiop->uio_iov->iov_len, size);
  770                         iov.iov_base = uiop->uio_iov->iov_base;
  771                         iov.iov_len = size;
  772                         uio.uio_iov = &iov;
  773                         uio.uio_iovcnt = 1;
  774                         uio.uio_offset = uiop->uio_offset;
  775                         uio.uio_resid = size;
  776                         uio.uio_segflg = UIO_USERSPACE;
  777                         uio.uio_rw = UIO_WRITE;
  778                         uio.uio_td = td;
  779                         iomode = NFSWRITE_FILESYNC;
  780                         error = ncl_writerpc(vp, &uio, cred, &iomode,
  781                             &must_commit, 0);
  782                         KASSERT((must_commit == 0), 
  783                                 ("ncl_directio_write: Did not commit write"));
  784                         if (error)
  785                                 return (error);
  786                         uiop->uio_offset += size;
  787                         uiop->uio_resid -= size;
  788                         if (uiop->uio_iov->iov_len <= size) {
  789                                 uiop->uio_iovcnt--;
  790                                 uiop->uio_iov++;
  791                         } else {
  792                                 uiop->uio_iov->iov_base = 
  793                                         (char *)uiop->uio_iov->iov_base + size;
  794                                 uiop->uio_iov->iov_len -= size;
  795                         }
  796                 }
  797         } else {
  798                 struct uio *t_uio;
  799                 struct iovec *t_iov;
  800                 struct buf *bp;
  801                 
  802                 /*
  803                  * Break up the write into blocksize chunks and hand these
  804                  * over to nfsiod's for write back.
  805                  * Unfortunately, this incurs a copy of the data. Since 
  806                  * the user could modify the buffer before the write is 
  807                  * initiated.
  808                  * 
  809                  * The obvious optimization here is that one of the 2 copies
  810                  * in the async write path can be eliminated by copying the
  811                  * data here directly into mbufs and passing the mbuf chain
  812                  * down. But that will require a fair amount of re-working
  813                  * of the code and can be done if there's enough interest
  814                  * in NFS directio access.
  815                  */
  816                 while (uiop->uio_resid > 0) {
  817                         size = MIN(uiop->uio_resid, wsize);
  818                         size = MIN(uiop->uio_iov->iov_len, size);
  819                         bp = getpbuf(&ncl_pbuf_freecnt);
  820                         t_uio = malloc(sizeof(struct uio), M_NFSDIRECTIO, M_WAITOK);
  821                         t_iov = malloc(sizeof(struct iovec), M_NFSDIRECTIO, M_WAITOK);
  822                         t_iov->iov_base = malloc(size, M_NFSDIRECTIO, M_WAITOK);
  823                         t_iov->iov_len = size;
  824                         t_uio->uio_iov = t_iov;
  825                         t_uio->uio_iovcnt = 1;
  826                         t_uio->uio_offset = uiop->uio_offset;
  827                         t_uio->uio_resid = size;
  828                         t_uio->uio_segflg = UIO_SYSSPACE;
  829                         t_uio->uio_rw = UIO_WRITE;
  830                         t_uio->uio_td = td;
  831                         KASSERT(uiop->uio_segflg == UIO_USERSPACE ||
  832                             uiop->uio_segflg == UIO_SYSSPACE,
  833                             ("nfs_directio_write: Bad uio_segflg"));
  834                         if (uiop->uio_segflg == UIO_USERSPACE) {
  835                                 error = copyin(uiop->uio_iov->iov_base,
  836                                     t_iov->iov_base, size);
  837                                 if (error != 0)
  838                                         goto err_free;
  839                         } else
  840                                 /*
  841                                  * UIO_SYSSPACE may never happen, but handle
  842                                  * it just in case it does.
  843                                  */
  844                                 bcopy(uiop->uio_iov->iov_base, t_iov->iov_base,
  845                                     size);
  846                         bp->b_flags |= B_DIRECT;
  847                         bp->b_iocmd = BIO_WRITE;
  848                         if (cred != NOCRED) {
  849                                 crhold(cred);
  850                                 bp->b_wcred = cred;
  851                         } else 
  852                                 bp->b_wcred = NOCRED;                   
  853                         bp->b_caller1 = (void *)t_uio;
  854                         bp->b_vp = vp;
  855                         error = ncl_asyncio(nmp, bp, NOCRED, td);
  856 err_free:
  857                         if (error) {
  858                                 free(t_iov->iov_base, M_NFSDIRECTIO);
  859                                 free(t_iov, M_NFSDIRECTIO);
  860                                 free(t_uio, M_NFSDIRECTIO);
  861                                 bp->b_vp = NULL;
  862                                 relpbuf(bp, &ncl_pbuf_freecnt);
  863                                 if (error == EINTR)
  864                                         return (error);
  865                                 goto do_sync;
  866                         }
  867                         uiop->uio_offset += size;
  868                         uiop->uio_resid -= size;
  869                         if (uiop->uio_iov->iov_len <= size) {
  870                                 uiop->uio_iovcnt--;
  871                                 uiop->uio_iov++;
  872                         } else {
  873                                 uiop->uio_iov->iov_base = 
  874                                         (char *)uiop->uio_iov->iov_base + size;
  875                                 uiop->uio_iov->iov_len -= size;
  876                         }
  877                 }
  878         }
  879         return (0);
  880 }
  881 
  882 /*
  883  * Vnode op for write using bio
  884  */
  885 int
  886 ncl_write(struct vop_write_args *ap)
  887 {
  888         int biosize;
  889         struct uio *uio = ap->a_uio;
  890         struct thread *td = uio->uio_td;
  891         struct vnode *vp = ap->a_vp;
  892         struct nfsnode *np = VTONFS(vp);
  893         struct ucred *cred = ap->a_cred;
  894         int ioflag = ap->a_ioflag;
  895         struct buf *bp;
  896         struct vattr vattr;
  897         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
  898         daddr_t lbn;
  899         int bcount;
  900         int n, on, error = 0;
  901         off_t tmp_off;
  902 
  903         KASSERT(uio->uio_rw == UIO_WRITE, ("ncl_write mode"));
  904         KASSERT(uio->uio_segflg != UIO_USERSPACE || uio->uio_td == curthread,
  905             ("ncl_write proc"));
  906         if (vp->v_type != VREG)
  907                 return (EIO);
  908         mtx_lock(&np->n_mtx);
  909         if (np->n_flag & NWRITEERR) {
  910                 np->n_flag &= ~NWRITEERR;
  911                 mtx_unlock(&np->n_mtx);
  912                 return (np->n_error);
  913         } else
  914                 mtx_unlock(&np->n_mtx);
  915         mtx_lock(&nmp->nm_mtx);
  916         if ((nmp->nm_flag & NFSMNT_NFSV3) != 0 &&
  917             (nmp->nm_state & NFSSTA_GOTFSINFO) == 0) {
  918                 mtx_unlock(&nmp->nm_mtx);
  919                 (void)ncl_fsinfo(nmp, vp, cred, td);
  920                 mtx_lock(&nmp->nm_mtx);
  921         }
  922         if (nmp->nm_wsize == 0)
  923                 (void) newnfs_iosize(nmp);
  924         mtx_unlock(&nmp->nm_mtx);
  925 
  926         /*
  927          * Synchronously flush pending buffers if we are in synchronous
  928          * mode or if we are appending.
  929          */
  930         if (ioflag & (IO_APPEND | IO_SYNC)) {
  931                 mtx_lock(&np->n_mtx);
  932                 if (np->n_flag & NMODIFIED) {
  933                         mtx_unlock(&np->n_mtx);
  934 #ifdef notyet /* Needs matching nonblock semantics elsewhere, too. */
  935                         /*
  936                          * Require non-blocking, synchronous writes to
  937                          * dirty files to inform the program it needs
  938                          * to fsync(2) explicitly.
  939                          */
  940                         if (ioflag & IO_NDELAY)
  941                                 return (EAGAIN);
  942 #endif
  943 flush_and_restart:
  944                         np->n_attrstamp = 0;
  945                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  946                         error = ncl_vinvalbuf(vp, V_SAVE, td, 1);
  947                         if (error)
  948                                 return (error);
  949                 } else
  950                         mtx_unlock(&np->n_mtx);
  951         }
  952 
  953         /*
  954          * If IO_APPEND then load uio_offset.  We restart here if we cannot
  955          * get the append lock.
  956          */
  957         if (ioflag & IO_APPEND) {
  958                 np->n_attrstamp = 0;
  959                 KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
  960                 error = VOP_GETATTR(vp, &vattr, cred);
  961                 if (error)
  962                         return (error);
  963                 mtx_lock(&np->n_mtx);
  964                 uio->uio_offset = np->n_size;
  965                 mtx_unlock(&np->n_mtx);
  966         }
  967 
  968         if (uio->uio_offset < 0)
  969                 return (EINVAL);
  970         tmp_off = uio->uio_offset + uio->uio_resid;
  971         if (tmp_off > nmp->nm_maxfilesize || tmp_off < uio->uio_offset)
  972                 return (EFBIG);
  973         if (uio->uio_resid == 0)
  974                 return (0);
  975 
  976         if (newnfs_directio_enable && (ioflag & IO_DIRECT) && vp->v_type == VREG)
  977                 return nfs_directio_write(vp, uio, cred, ioflag);
  978 
  979         /*
  980          * Maybe this should be above the vnode op call, but so long as
  981          * file servers have no limits, i don't think it matters
  982          */
  983         if (vn_rlimit_fsize(vp, uio, td))
  984                 return (EFBIG);
  985 
  986         biosize = vp->v_bufobj.bo_bsize;
  987         /*
  988          * Find all of this file's B_NEEDCOMMIT buffers.  If our writes
  989          * would exceed the local maximum per-file write commit size when
  990          * combined with those, we must decide whether to flush,
  991          * go synchronous, or return error.  We don't bother checking
  992          * IO_UNIT -- we just make all writes atomic anyway, as there's
  993          * no point optimizing for something that really won't ever happen.
  994          */
  995         if (!(ioflag & IO_SYNC)) {
  996                 int nflag;
  997 
  998                 mtx_lock(&np->n_mtx);
  999                 nflag = np->n_flag;
 1000                 mtx_unlock(&np->n_mtx);         
 1001                 int needrestart = 0;
 1002                 if (nmp->nm_wcommitsize < uio->uio_resid) {
 1003                         /*
 1004                          * If this request could not possibly be completed
 1005                          * without exceeding the maximum outstanding write
 1006                          * commit size, see if we can convert it into a
 1007                          * synchronous write operation.
 1008                          */
 1009                         if (ioflag & IO_NDELAY)
 1010                                 return (EAGAIN);
 1011                         ioflag |= IO_SYNC;
 1012                         if (nflag & NMODIFIED)
 1013                                 needrestart = 1;
 1014                 } else if (nflag & NMODIFIED) {
 1015                         int wouldcommit = 0;
 1016                         BO_LOCK(&vp->v_bufobj);
 1017                         if (vp->v_bufobj.bo_dirty.bv_cnt != 0) {
 1018                                 TAILQ_FOREACH(bp, &vp->v_bufobj.bo_dirty.bv_hd,
 1019                                     b_bobufs) {
 1020                                         if (bp->b_flags & B_NEEDCOMMIT)
 1021                                                 wouldcommit += bp->b_bcount;
 1022                                 }
 1023                         }
 1024                         BO_UNLOCK(&vp->v_bufobj);
 1025                         /*
 1026                          * Since we're not operating synchronously and
 1027                          * bypassing the buffer cache, we are in a commit
 1028                          * and holding all of these buffers whether
 1029                          * transmitted or not.  If not limited, this
 1030                          * will lead to the buffer cache deadlocking,
 1031                          * as no one else can flush our uncommitted buffers.
 1032                          */
 1033                         wouldcommit += uio->uio_resid;
 1034                         /*
 1035                          * If we would initially exceed the maximum
 1036                          * outstanding write commit size, flush and restart.
 1037                          */
 1038                         if (wouldcommit > nmp->nm_wcommitsize)
 1039                                 needrestart = 1;
 1040                 }
 1041                 if (needrestart)
 1042                         goto flush_and_restart;
 1043         }
 1044 
 1045         do {
 1046                 NFSINCRGLOBAL(newnfsstats.biocache_writes);
 1047                 lbn = uio->uio_offset / biosize;
 1048                 on = uio->uio_offset & (biosize-1);
 1049                 n = MIN((unsigned)(biosize - on), uio->uio_resid);
 1050 again:
 1051                 /*
 1052                  * Handle direct append and file extension cases, calculate
 1053                  * unaligned buffer size.
 1054                  */
 1055                 mtx_lock(&np->n_mtx);
 1056                 if (uio->uio_offset == np->n_size && n) {
 1057                         mtx_unlock(&np->n_mtx);
 1058                         /*
 1059                          * Get the buffer (in its pre-append state to maintain
 1060                          * B_CACHE if it was previously set).  Resize the
 1061                          * nfsnode after we have locked the buffer to prevent
 1062                          * readers from reading garbage.
 1063                          */
 1064                         bcount = on;
 1065                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1066 
 1067                         if (bp != NULL) {
 1068                                 long save;
 1069 
 1070                                 mtx_lock(&np->n_mtx);
 1071                                 np->n_size = uio->uio_offset + n;
 1072                                 np->n_flag |= NMODIFIED;
 1073                                 vnode_pager_setsize(vp, np->n_size);
 1074                                 mtx_unlock(&np->n_mtx);
 1075 
 1076                                 save = bp->b_flags & B_CACHE;
 1077                                 bcount += n;
 1078                                 allocbuf(bp, bcount);
 1079                                 bp->b_flags |= save;
 1080                         }
 1081                 } else {
 1082                         /*
 1083                          * Obtain the locked cache block first, and then
 1084                          * adjust the file's size as appropriate.
 1085                          */
 1086                         bcount = on + n;
 1087                         if ((off_t)lbn * biosize + bcount < np->n_size) {
 1088                                 if ((off_t)(lbn + 1) * biosize < np->n_size)
 1089                                         bcount = biosize;
 1090                                 else
 1091                                         bcount = np->n_size - (off_t)lbn * biosize;
 1092                         }
 1093                         mtx_unlock(&np->n_mtx);
 1094                         bp = nfs_getcacheblk(vp, lbn, bcount, td);
 1095                         mtx_lock(&np->n_mtx);
 1096                         if (uio->uio_offset + n > np->n_size) {
 1097                                 np->n_size = uio->uio_offset + n;
 1098                                 np->n_flag |= NMODIFIED;
 1099                                 vnode_pager_setsize(vp, np->n_size);
 1100                         }
 1101                         mtx_unlock(&np->n_mtx);
 1102                 }
 1103 
 1104                 if (!bp) {
 1105                         error = newnfs_sigintr(nmp, td);
 1106                         if (!error)
 1107                                 error = EINTR;
 1108                         break;
 1109                 }
 1110 
 1111                 /*
 1112                  * Issue a READ if B_CACHE is not set.  In special-append
 1113                  * mode, B_CACHE is based on the buffer prior to the write
 1114                  * op and is typically set, avoiding the read.  If a read
 1115                  * is required in special append mode, the server will
 1116                  * probably send us a short-read since we extended the file
 1117                  * on our end, resulting in b_resid == 0 and, thusly,
 1118                  * B_CACHE getting set.
 1119                  *
 1120                  * We can also avoid issuing the read if the write covers
 1121                  * the entire buffer.  We have to make sure the buffer state
 1122                  * is reasonable in this case since we will not be initiating
 1123                  * I/O.  See the comments in kern/vfs_bio.c's getblk() for
 1124                  * more information.
 1125                  *
 1126                  * B_CACHE may also be set due to the buffer being cached
 1127                  * normally.
 1128                  */
 1129 
 1130                 if (on == 0 && n == bcount) {
 1131                         bp->b_flags |= B_CACHE;
 1132                         bp->b_flags &= ~B_INVAL;
 1133                         bp->b_ioflags &= ~BIO_ERROR;
 1134                 }
 1135 
 1136                 if ((bp->b_flags & B_CACHE) == 0) {
 1137                         bp->b_iocmd = BIO_READ;
 1138                         vfs_busy_pages(bp, 0);
 1139                         error = ncl_doio(vp, bp, cred, td, 0);
 1140                         if (error) {
 1141                                 brelse(bp);
 1142                                 break;
 1143                         }
 1144                 }
 1145                 if (bp->b_wcred == NOCRED)
 1146                         bp->b_wcred = crhold(cred);
 1147                 mtx_lock(&np->n_mtx);
 1148                 np->n_flag |= NMODIFIED;
 1149                 mtx_unlock(&np->n_mtx);
 1150 
 1151                 /*
 1152                  * If dirtyend exceeds file size, chop it down.  This should
 1153                  * not normally occur but there is an append race where it
 1154                  * might occur XXX, so we log it.
 1155                  *
 1156                  * If the chopping creates a reverse-indexed or degenerate
 1157                  * situation with dirtyoff/end, we 0 both of them.
 1158                  */
 1159 
 1160                 if (bp->b_dirtyend > bcount) {
 1161                         ncl_printf("NFS append race @%lx:%d\n",
 1162                             (long)bp->b_blkno * DEV_BSIZE,
 1163                             bp->b_dirtyend - bcount);
 1164                         bp->b_dirtyend = bcount;
 1165                 }
 1166 
 1167                 if (bp->b_dirtyoff >= bp->b_dirtyend)
 1168                         bp->b_dirtyoff = bp->b_dirtyend = 0;
 1169 
 1170                 /*
 1171                  * If the new write will leave a contiguous dirty
 1172                  * area, just update the b_dirtyoff and b_dirtyend,
 1173                  * otherwise force a write rpc of the old dirty area.
 1174                  *
 1175                  * While it is possible to merge discontiguous writes due to
 1176                  * our having a B_CACHE buffer ( and thus valid read data
 1177                  * for the hole), we don't because it could lead to
 1178                  * significant cache coherency problems with multiple clients,
 1179                  * especially if locking is implemented later on.
 1180                  *
 1181                  * As an optimization we could theoretically maintain
 1182                  * a linked list of discontinuous areas, but we would still
 1183                  * have to commit them separately so there isn't much
 1184                  * advantage to it except perhaps a bit of asynchronization.
 1185                  */
 1186 
 1187                 if (bp->b_dirtyend > 0 &&
 1188                     (on > bp->b_dirtyend || (on + n) < bp->b_dirtyoff)) {
 1189                         if (bwrite(bp) == EINTR) {
 1190                                 error = EINTR;
 1191                                 break;
 1192                         }
 1193                         goto again;
 1194                 }
 1195 
 1196                 error = uiomove((char *)bp->b_data + on, n, uio);
 1197 
 1198                 /*
 1199                  * Since this block is being modified, it must be written
 1200                  * again and not just committed.  Since write clustering does
 1201                  * not work for the stage 1 data write, only the stage 2
 1202                  * commit rpc, we have to clear B_CLUSTEROK as well.
 1203                  */
 1204                 bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1205 
 1206                 if (error) {
 1207                         bp->b_ioflags |= BIO_ERROR;
 1208                         brelse(bp);
 1209                         break;
 1210                 }
 1211 
 1212                 /*
 1213                  * Only update dirtyoff/dirtyend if not a degenerate
 1214                  * condition.
 1215                  */
 1216                 if (n) {
 1217                         if (bp->b_dirtyend > 0) {
 1218                                 bp->b_dirtyoff = min(on, bp->b_dirtyoff);
 1219                                 bp->b_dirtyend = max((on + n), bp->b_dirtyend);
 1220                         } else {
 1221                                 bp->b_dirtyoff = on;
 1222                                 bp->b_dirtyend = on + n;
 1223                         }
 1224                         vfs_bio_set_valid(bp, on, n);
 1225                 }
 1226 
 1227                 /*
 1228                  * If IO_SYNC do bwrite().
 1229                  *
 1230                  * IO_INVAL appears to be unused.  The idea appears to be
 1231                  * to turn off caching in this case.  Very odd.  XXX
 1232                  */
 1233                 if ((ioflag & IO_SYNC)) {
 1234                         if (ioflag & IO_INVAL)
 1235                                 bp->b_flags |= B_NOCACHE;
 1236                         error = bwrite(bp);
 1237                         if (error)
 1238                                 break;
 1239                 } else if ((n + on) == biosize) {
 1240                         bp->b_flags |= B_ASYNC;
 1241                         (void) ncl_writebp(bp, 0, NULL);
 1242                 } else {
 1243                         bdwrite(bp);
 1244                 }
 1245         } while (uio->uio_resid > 0 && n > 0);
 1246 
 1247         return (error);
 1248 }
 1249 
 1250 /*
 1251  * Get an nfs cache block.
 1252  *
 1253  * Allocate a new one if the block isn't currently in the cache
 1254  * and return the block marked busy. If the calling process is
 1255  * interrupted by a signal for an interruptible mount point, return
 1256  * NULL.
 1257  *
 1258  * The caller must carefully deal with the possible B_INVAL state of
 1259  * the buffer.  ncl_doio() clears B_INVAL (and ncl_asyncio() clears it
 1260  * indirectly), so synchronous reads can be issued without worrying about
 1261  * the B_INVAL state.  We have to be a little more careful when dealing
 1262  * with writes (see comments in nfs_write()) when extending a file past
 1263  * its EOF.
 1264  */
 1265 static struct buf *
 1266 nfs_getcacheblk(struct vnode *vp, daddr_t bn, int size, struct thread *td)
 1267 {
 1268         struct buf *bp;
 1269         struct mount *mp;
 1270         struct nfsmount *nmp;
 1271 
 1272         mp = vp->v_mount;
 1273         nmp = VFSTONFS(mp);
 1274 
 1275         if (nmp->nm_flag & NFSMNT_INT) {
 1276                 sigset_t oldset;
 1277 
 1278                 newnfs_set_sigmask(td, &oldset);
 1279                 bp = getblk(vp, bn, size, NFS_PCATCH, 0, 0);
 1280                 newnfs_restore_sigmask(td, &oldset);
 1281                 while (bp == NULL) {
 1282                         if (newnfs_sigintr(nmp, td))
 1283                                 return (NULL);
 1284                         bp = getblk(vp, bn, size, 0, 2 * hz, 0);
 1285                 }
 1286         } else {
 1287                 bp = getblk(vp, bn, size, 0, 0, 0);
 1288         }
 1289 
 1290         if (vp->v_type == VREG)
 1291                 bp->b_blkno = bn * (vp->v_bufobj.bo_bsize / DEV_BSIZE);
 1292         return (bp);
 1293 }
 1294 
 1295 /*
 1296  * Flush and invalidate all dirty buffers. If another process is already
 1297  * doing the flush, just wait for completion.
 1298  */
 1299 int
 1300 ncl_vinvalbuf(struct vnode *vp, int flags, struct thread *td, int intrflg)
 1301 {
 1302         struct nfsnode *np = VTONFS(vp);
 1303         struct nfsmount *nmp = VFSTONFS(vp->v_mount);
 1304         int error = 0, slpflag, slptimeo;
 1305         int old_lock = 0;
 1306 
 1307         ASSERT_VOP_LOCKED(vp, "ncl_vinvalbuf");
 1308 
 1309         if ((nmp->nm_flag & NFSMNT_INT) == 0)
 1310                 intrflg = 0;
 1311         if ((nmp->nm_mountp->mnt_kern_flag & MNTK_UNMOUNTF))
 1312                 intrflg = 1;
 1313         if (intrflg) {
 1314                 slpflag = NFS_PCATCH;
 1315                 slptimeo = 2 * hz;
 1316         } else {
 1317                 slpflag = 0;
 1318                 slptimeo = 0;
 1319         }
 1320 
 1321         old_lock = ncl_upgrade_vnlock(vp);
 1322         if (vp->v_iflag & VI_DOOMED) {
 1323                 /*
 1324                  * Since vgonel() uses the generic vinvalbuf() to flush
 1325                  * dirty buffers and it does not call this function, it
 1326                  * is safe to just return OK when VI_DOOMED is set.
 1327                  */
 1328                 ncl_downgrade_vnlock(vp, old_lock);
 1329                 return (0);
 1330         }
 1331 
 1332         /*
 1333          * Now, flush as required.
 1334          */
 1335         if ((flags & V_SAVE) && (vp->v_bufobj.bo_object != NULL)) {
 1336                 VM_OBJECT_LOCK(vp->v_bufobj.bo_object);
 1337                 vm_object_page_clean(vp->v_bufobj.bo_object, 0, 0, OBJPC_SYNC);
 1338                 VM_OBJECT_UNLOCK(vp->v_bufobj.bo_object);
 1339                 /*
 1340                  * If the page clean was interrupted, fail the invalidation.
 1341                  * Not doing so, we run the risk of losing dirty pages in the 
 1342                  * vinvalbuf() call below.
 1343                  */
 1344                 if (intrflg && (error = newnfs_sigintr(nmp, td)))
 1345                         goto out;
 1346         }
 1347 
 1348         error = vinvalbuf(vp, flags, slpflag, 0);
 1349         while (error) {
 1350                 if (intrflg && (error = newnfs_sigintr(nmp, td)))
 1351                         goto out;
 1352                 error = vinvalbuf(vp, flags, 0, slptimeo);
 1353         }
 1354         mtx_lock(&np->n_mtx);
 1355         if (np->n_directio_asyncwr == 0)
 1356                 np->n_flag &= ~NMODIFIED;
 1357         mtx_unlock(&np->n_mtx);
 1358 out:
 1359         ncl_downgrade_vnlock(vp, old_lock);
 1360         return error;
 1361 }
 1362 
 1363 /*
 1364  * Initiate asynchronous I/O. Return an error if no nfsiods are available.
 1365  * This is mainly to avoid queueing async I/O requests when the nfsiods
 1366  * are all hung on a dead server.
 1367  *
 1368  * Note: ncl_asyncio() does not clear (BIO_ERROR|B_INVAL) but when the bp
 1369  * is eventually dequeued by the async daemon, ncl_doio() *will*.
 1370  */
 1371 int
 1372 ncl_asyncio(struct nfsmount *nmp, struct buf *bp, struct ucred *cred, struct thread *td)
 1373 {
 1374         int iod;
 1375         int gotiod;
 1376         int slpflag = 0;
 1377         int slptimeo = 0;
 1378         int error, error2;
 1379 
 1380         /*
 1381          * Commits are usually short and sweet so lets save some cpu and
 1382          * leave the async daemons for more important rpc's (such as reads
 1383          * and writes).
 1384          */
 1385         mtx_lock(&ncl_iod_mutex);
 1386         if (bp->b_iocmd == BIO_WRITE && (bp->b_flags & B_NEEDCOMMIT) &&
 1387             (nmp->nm_bufqiods > ncl_numasync / 2)) {
 1388                 mtx_unlock(&ncl_iod_mutex);
 1389                 return(EIO);
 1390         }
 1391 again:
 1392         if (nmp->nm_flag & NFSMNT_INT)
 1393                 slpflag = NFS_PCATCH;
 1394         gotiod = FALSE;
 1395 
 1396         /*
 1397          * Find a free iod to process this request.
 1398          */
 1399         for (iod = 0; iod < ncl_numasync; iod++)
 1400                 if (ncl_iodwant[iod] == NFSIOD_AVAILABLE) {
 1401                         gotiod = TRUE;
 1402                         break;
 1403                 }
 1404 
 1405         /*
 1406          * Try to create one if none are free.
 1407          */
 1408         if (!gotiod)
 1409                 ncl_nfsiodnew();
 1410         else {
 1411                 /*
 1412                  * Found one, so wake it up and tell it which
 1413                  * mount to process.
 1414                  */
 1415                 NFS_DPF(ASYNCIO, ("ncl_asyncio: waking iod %d for mount %p\n",
 1416                     iod, nmp));
 1417                 ncl_iodwant[iod] = NFSIOD_NOT_AVAILABLE;
 1418                 ncl_iodmount[iod] = nmp;
 1419                 nmp->nm_bufqiods++;
 1420                 wakeup(&ncl_iodwant[iod]);
 1421         }
 1422 
 1423         /*
 1424          * If none are free, we may already have an iod working on this mount
 1425          * point.  If so, it will process our request.
 1426          */
 1427         if (!gotiod) {
 1428                 if (nmp->nm_bufqiods > 0) {
 1429                         NFS_DPF(ASYNCIO,
 1430                                 ("ncl_asyncio: %d iods are already processing mount %p\n",
 1431                                  nmp->nm_bufqiods, nmp));
 1432                         gotiod = TRUE;
 1433                 }
 1434         }
 1435 
 1436         /*
 1437          * If we have an iod which can process the request, then queue
 1438          * the buffer.
 1439          */
 1440         if (gotiod) {
 1441                 /*
 1442                  * Ensure that the queue never grows too large.  We still want
 1443                  * to asynchronize so we block rather then return EIO.
 1444                  */
 1445                 while (nmp->nm_bufqlen >= 2*ncl_numasync) {
 1446                         NFS_DPF(ASYNCIO,
 1447                                 ("ncl_asyncio: waiting for mount %p queue to drain\n", nmp));
 1448                         nmp->nm_bufqwant = TRUE;
 1449                         error = newnfs_msleep(td, &nmp->nm_bufq, 
 1450                             &ncl_iod_mutex, slpflag | PRIBIO, "nfsaio",
 1451                            slptimeo);
 1452                         if (error) {
 1453                                 error2 = newnfs_sigintr(nmp, td);
 1454                                 if (error2) {
 1455                                         mtx_unlock(&ncl_iod_mutex);                                     
 1456                                         return (error2);
 1457                                 }
 1458                                 if (slpflag == NFS_PCATCH) {
 1459                                         slpflag = 0;
 1460                                         slptimeo = 2 * hz;
 1461                                 }
 1462                         }
 1463                         /*
 1464                          * We might have lost our iod while sleeping,
 1465                          * so check and loop if nescessary.
 1466                          */
 1467                         goto again;
 1468                 }
 1469 
 1470                 /* We might have lost our nfsiod */
 1471                 if (nmp->nm_bufqiods == 0) {
 1472                         NFS_DPF(ASYNCIO,
 1473                                 ("ncl_asyncio: no iods after mount %p queue was drained, looping\n", nmp));
 1474                         goto again;
 1475                 }
 1476 
 1477                 if (bp->b_iocmd == BIO_READ) {
 1478                         if (bp->b_rcred == NOCRED && cred != NOCRED)
 1479                                 bp->b_rcred = crhold(cred);
 1480                 } else {
 1481                         if (bp->b_wcred == NOCRED && cred != NOCRED)
 1482                                 bp->b_wcred = crhold(cred);
 1483                 }
 1484 
 1485                 if (bp->b_flags & B_REMFREE)
 1486                         bremfreef(bp);
 1487                 BUF_KERNPROC(bp);
 1488                 TAILQ_INSERT_TAIL(&nmp->nm_bufq, bp, b_freelist);
 1489                 nmp->nm_bufqlen++;
 1490                 if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1491                         mtx_lock(&(VTONFS(bp->b_vp))->n_mtx);                   
 1492                         VTONFS(bp->b_vp)->n_flag |= NMODIFIED;
 1493                         VTONFS(bp->b_vp)->n_directio_asyncwr++;
 1494                         mtx_unlock(&(VTONFS(bp->b_vp))->n_mtx);
 1495                 }
 1496                 mtx_unlock(&ncl_iod_mutex);
 1497                 return (0);
 1498         }
 1499 
 1500         mtx_unlock(&ncl_iod_mutex);
 1501 
 1502         /*
 1503          * All the iods are busy on other mounts, so return EIO to
 1504          * force the caller to process the i/o synchronously.
 1505          */
 1506         NFS_DPF(ASYNCIO, ("ncl_asyncio: no iods available, i/o is synchronous\n"));
 1507         return (EIO);
 1508 }
 1509 
 1510 void
 1511 ncl_doio_directwrite(struct buf *bp)
 1512 {
 1513         int iomode, must_commit;
 1514         struct uio *uiop = (struct uio *)bp->b_caller1;
 1515         char *iov_base = uiop->uio_iov->iov_base;
 1516         
 1517         iomode = NFSWRITE_FILESYNC;
 1518         uiop->uio_td = NULL; /* NULL since we're in nfsiod */
 1519         ncl_writerpc(bp->b_vp, uiop, bp->b_wcred, &iomode, &must_commit, 0);
 1520         KASSERT((must_commit == 0), ("ncl_doio_directwrite: Did not commit write"));
 1521         free(iov_base, M_NFSDIRECTIO);
 1522         free(uiop->uio_iov, M_NFSDIRECTIO);
 1523         free(uiop, M_NFSDIRECTIO);
 1524         if ((bp->b_flags & B_DIRECT) && bp->b_iocmd == BIO_WRITE) {
 1525                 struct nfsnode *np = VTONFS(bp->b_vp);
 1526                 mtx_lock(&np->n_mtx);
 1527                 np->n_directio_asyncwr--;
 1528                 if (np->n_directio_asyncwr == 0) {
 1529                         np->n_flag &= ~NMODIFIED;
 1530                         if ((np->n_flag & NFSYNCWAIT)) {
 1531                                 np->n_flag &= ~NFSYNCWAIT;
 1532                                 wakeup((caddr_t)&np->n_directio_asyncwr);
 1533                         }
 1534                 }
 1535                 mtx_unlock(&np->n_mtx);
 1536         }
 1537         bp->b_vp = NULL;
 1538         relpbuf(bp, &ncl_pbuf_freecnt);
 1539 }
 1540 
 1541 /*
 1542  * Do an I/O operation to/from a cache block. This may be called
 1543  * synchronously or from an nfsiod.
 1544  */
 1545 int
 1546 ncl_doio(struct vnode *vp, struct buf *bp, struct ucred *cr, struct thread *td,
 1547     int called_from_strategy)
 1548 {
 1549         struct uio *uiop;
 1550         struct nfsnode *np;
 1551         struct nfsmount *nmp;
 1552         int error = 0, iomode, must_commit = 0;
 1553         struct uio uio;
 1554         struct iovec io;
 1555         struct proc *p = td ? td->td_proc : NULL;
 1556         uint8_t iocmd;
 1557         
 1558         np = VTONFS(vp);
 1559         nmp = VFSTONFS(vp->v_mount);
 1560         uiop = &uio;
 1561         uiop->uio_iov = &io;
 1562         uiop->uio_iovcnt = 1;
 1563         uiop->uio_segflg = UIO_SYSSPACE;
 1564         uiop->uio_td = td;
 1565 
 1566         /*
 1567          * clear BIO_ERROR and B_INVAL state prior to initiating the I/O.  We
 1568          * do this here so we do not have to do it in all the code that
 1569          * calls us.
 1570          */
 1571         bp->b_flags &= ~B_INVAL;
 1572         bp->b_ioflags &= ~BIO_ERROR;
 1573 
 1574         KASSERT(!(bp->b_flags & B_DONE), ("ncl_doio: bp %p already marked done", bp));
 1575         iocmd = bp->b_iocmd;
 1576         if (iocmd == BIO_READ) {
 1577             io.iov_len = uiop->uio_resid = bp->b_bcount;
 1578             io.iov_base = bp->b_data;
 1579             uiop->uio_rw = UIO_READ;
 1580 
 1581             switch (vp->v_type) {
 1582             case VREG:
 1583                 uiop->uio_offset = ((off_t)bp->b_blkno) * DEV_BSIZE;
 1584                 NFSINCRGLOBAL(newnfsstats.read_bios);
 1585                 error = ncl_readrpc(vp, uiop, cr);
 1586 
 1587                 if (!error) {
 1588                     if (uiop->uio_resid) {
 1589                         /*
 1590                          * If we had a short read with no error, we must have
 1591                          * hit a file hole.  We should zero-fill the remainder.
 1592                          * This can also occur if the server hits the file EOF.
 1593                          *
 1594                          * Holes used to be able to occur due to pending
 1595                          * writes, but that is not possible any longer.
 1596                          */
 1597                         int nread = bp->b_bcount - uiop->uio_resid;
 1598                         ssize_t left = uiop->uio_resid;
 1599 
 1600                         if (left > 0)
 1601                                 bzero((char *)bp->b_data + nread, left);
 1602                         uiop->uio_resid = 0;
 1603                     }
 1604                 }
 1605                 /* ASSERT_VOP_LOCKED(vp, "ncl_doio"); */
 1606                 if (p && (vp->v_vflag & VV_TEXT)) {
 1607                         mtx_lock(&np->n_mtx);
 1608                         if (NFS_TIMESPEC_COMPARE(&np->n_mtime, &np->n_vattr.na_mtime)) {
 1609                                 mtx_unlock(&np->n_mtx);
 1610                                 PROC_LOCK(p);
 1611                                 killproc(p, "text file modification");
 1612                                 PROC_UNLOCK(p);
 1613                         } else
 1614                                 mtx_unlock(&np->n_mtx);
 1615                 }
 1616                 break;
 1617             case VLNK:
 1618                 uiop->uio_offset = (off_t)0;
 1619                 NFSINCRGLOBAL(newnfsstats.readlink_bios);
 1620                 error = ncl_readlinkrpc(vp, uiop, cr);
 1621                 break;
 1622             case VDIR:
 1623                 NFSINCRGLOBAL(newnfsstats.readdir_bios);
 1624                 uiop->uio_offset = ((u_quad_t)bp->b_lblkno) * NFS_DIRBLKSIZ;
 1625                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) != 0) {
 1626                         error = ncl_readdirplusrpc(vp, uiop, cr, td);
 1627                         if (error == NFSERR_NOTSUPP)
 1628                                 nmp->nm_flag &= ~NFSMNT_RDIRPLUS;
 1629                 }
 1630                 if ((nmp->nm_flag & NFSMNT_RDIRPLUS) == 0)
 1631                         error = ncl_readdirrpc(vp, uiop, cr, td);
 1632                 /*
 1633                  * end-of-directory sets B_INVAL but does not generate an
 1634                  * error.
 1635                  */
 1636                 if (error == 0 && uiop->uio_resid == bp->b_bcount)
 1637                         bp->b_flags |= B_INVAL;
 1638                 break;
 1639             default:
 1640                 ncl_printf("ncl_doio:  type %x unexpected\n", vp->v_type);
 1641                 break;
 1642             };
 1643             if (error) {
 1644                 bp->b_ioflags |= BIO_ERROR;
 1645                 bp->b_error = error;
 1646             }
 1647         } else {
 1648             /*
 1649              * If we only need to commit, try to commit
 1650              */
 1651             if (bp->b_flags & B_NEEDCOMMIT) {
 1652                     int retv;
 1653                     off_t off;
 1654 
 1655                     off = ((u_quad_t)bp->b_blkno) * DEV_BSIZE + bp->b_dirtyoff;
 1656                     retv = ncl_commit(vp, off, bp->b_dirtyend-bp->b_dirtyoff,
 1657                         bp->b_wcred, td);
 1658                     if (retv == 0) {
 1659                             bp->b_dirtyoff = bp->b_dirtyend = 0;
 1660                             bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1661                             bp->b_resid = 0;
 1662                             bufdone(bp);
 1663                             return (0);
 1664                     }
 1665                     if (retv == NFSERR_STALEWRITEVERF) {
 1666                             ncl_clearcommit(vp->v_mount);
 1667                     }
 1668             }
 1669 
 1670             /*
 1671              * Setup for actual write
 1672              */
 1673             mtx_lock(&np->n_mtx);
 1674             if ((off_t)bp->b_blkno * DEV_BSIZE + bp->b_dirtyend > np->n_size)
 1675                 bp->b_dirtyend = np->n_size - (off_t)bp->b_blkno * DEV_BSIZE;
 1676             mtx_unlock(&np->n_mtx);
 1677 
 1678             if (bp->b_dirtyend > bp->b_dirtyoff) {
 1679                 io.iov_len = uiop->uio_resid = bp->b_dirtyend
 1680                     - bp->b_dirtyoff;
 1681                 uiop->uio_offset = (off_t)bp->b_blkno * DEV_BSIZE
 1682                     + bp->b_dirtyoff;
 1683                 io.iov_base = (char *)bp->b_data + bp->b_dirtyoff;
 1684                 uiop->uio_rw = UIO_WRITE;
 1685                 NFSINCRGLOBAL(newnfsstats.write_bios);
 1686 
 1687                 if ((bp->b_flags & (B_ASYNC | B_NEEDCOMMIT | B_NOCACHE | B_CLUSTER)) == B_ASYNC)
 1688                     iomode = NFSWRITE_UNSTABLE;
 1689                 else
 1690                     iomode = NFSWRITE_FILESYNC;
 1691 
 1692                 error = ncl_writerpc(vp, uiop, cr, &iomode, &must_commit,
 1693                     called_from_strategy);
 1694 
 1695                 /*
 1696                  * When setting B_NEEDCOMMIT also set B_CLUSTEROK to try
 1697                  * to cluster the buffers needing commit.  This will allow
 1698                  * the system to submit a single commit rpc for the whole
 1699                  * cluster.  We can do this even if the buffer is not 100%
 1700                  * dirty (relative to the NFS blocksize), so we optimize the
 1701                  * append-to-file-case.
 1702                  *
 1703                  * (when clearing B_NEEDCOMMIT, B_CLUSTEROK must also be
 1704                  * cleared because write clustering only works for commit
 1705                  * rpc's, not for the data portion of the write).
 1706                  */
 1707 
 1708                 if (!error && iomode == NFSWRITE_UNSTABLE) {
 1709                     bp->b_flags |= B_NEEDCOMMIT;
 1710                     if (bp->b_dirtyoff == 0
 1711                         && bp->b_dirtyend == bp->b_bcount)
 1712                         bp->b_flags |= B_CLUSTEROK;
 1713                 } else {
 1714                     bp->b_flags &= ~(B_NEEDCOMMIT | B_CLUSTEROK);
 1715                 }
 1716 
 1717                 /*
 1718                  * For an interrupted write, the buffer is still valid
 1719                  * and the write hasn't been pushed to the server yet,
 1720                  * so we can't set BIO_ERROR and report the interruption
 1721                  * by setting B_EINTR. For the B_ASYNC case, B_EINTR
 1722                  * is not relevant, so the rpc attempt is essentially
 1723                  * a noop.  For the case of a V3 write rpc not being
 1724                  * committed to stable storage, the block is still
 1725                  * dirty and requires either a commit rpc or another
 1726                  * write rpc with iomode == NFSV3WRITE_FILESYNC before
 1727                  * the block is reused. This is indicated by setting
 1728                  * the B_DELWRI and B_NEEDCOMMIT flags.
 1729                  *
 1730                  * EIO is returned by ncl_writerpc() to indicate a recoverable
 1731                  * write error and is handled as above, except that
 1732                  * B_EINTR isn't set. One cause of this is a stale stateid
 1733                  * error for the RPC that indicates recovery is required,
 1734                  * when called with called_from_strategy != 0.
 1735                  *
 1736                  * If the buffer is marked B_PAGING, it does not reside on
 1737                  * the vp's paging queues so we cannot call bdirty().  The
 1738                  * bp in this case is not an NFS cache block so we should
 1739                  * be safe. XXX
 1740                  *
 1741                  * The logic below breaks up errors into recoverable and 
 1742                  * unrecoverable. For the former, we clear B_INVAL|B_NOCACHE
 1743                  * and keep the buffer around for potential write retries.
 1744                  * For the latter (eg ESTALE), we toss the buffer away (B_INVAL)
 1745                  * and save the error in the nfsnode. This is less than ideal 
 1746                  * but necessary. Keeping such buffers around could potentially
 1747                  * cause buffer exhaustion eventually (they can never be written
 1748                  * out, so will get constantly be re-dirtied). It also causes
 1749                  * all sorts of vfs panics. For non-recoverable write errors, 
 1750                  * also invalidate the attrcache, so we'll be forced to go over
 1751                  * the wire for this object, returning an error to user on next
 1752                  * call (most of the time).
 1753                  */
 1754                 if (error == EINTR || error == EIO || error == ETIMEDOUT
 1755                     || (!error && (bp->b_flags & B_NEEDCOMMIT))) {
 1756                         int s;
 1757 
 1758                         s = splbio();
 1759                         bp->b_flags &= ~(B_INVAL|B_NOCACHE);
 1760                         if ((bp->b_flags & B_PAGING) == 0) {
 1761                             bdirty(bp);
 1762                             bp->b_flags &= ~B_DONE;
 1763                         }
 1764                         if ((error == EINTR || error == ETIMEDOUT) &&
 1765                             (bp->b_flags & B_ASYNC) == 0)
 1766                             bp->b_flags |= B_EINTR;
 1767                         splx(s);
 1768                 } else {
 1769                     if (error) {
 1770                         bp->b_ioflags |= BIO_ERROR;
 1771                         bp->b_flags |= B_INVAL;
 1772                         bp->b_error = np->n_error = error;
 1773                         mtx_lock(&np->n_mtx);
 1774                         np->n_flag |= NWRITEERR;
 1775                         np->n_attrstamp = 0;
 1776                         KDTRACE_NFS_ATTRCACHE_FLUSH_DONE(vp);
 1777                         mtx_unlock(&np->n_mtx);
 1778                     }
 1779                     bp->b_dirtyoff = bp->b_dirtyend = 0;
 1780                 }
 1781             } else {
 1782                 bp->b_resid = 0;
 1783                 bufdone(bp);
 1784                 return (0);
 1785             }
 1786         }
 1787         bp->b_resid = uiop->uio_resid;
 1788         if (must_commit)
 1789             ncl_clearcommit(vp->v_mount);
 1790         bufdone(bp);
 1791         return (error);
 1792 }
 1793 
 1794 /*
 1795  * Used to aid in handling ftruncate() operations on the NFS client side.
 1796  * Truncation creates a number of special problems for NFS.  We have to
 1797  * throw away VM pages and buffer cache buffers that are beyond EOF, and
 1798  * we have to properly handle VM pages or (potentially dirty) buffers
 1799  * that straddle the truncation point.
 1800  */
 1801 
 1802 int
 1803 ncl_meta_setsize(struct vnode *vp, struct ucred *cred, struct thread *td, u_quad_t nsize)
 1804 {
 1805         struct nfsnode *np = VTONFS(vp);
 1806         u_quad_t tsize;
 1807         int biosize = vp->v_bufobj.bo_bsize;
 1808         int error = 0;
 1809 
 1810         mtx_lock(&np->n_mtx);
 1811         tsize = np->n_size;
 1812         np->n_size = nsize;
 1813         mtx_unlock(&np->n_mtx);
 1814 
 1815         if (nsize < tsize) {
 1816                 struct buf *bp;
 1817                 daddr_t lbn;
 1818                 int bufsize;
 1819 
 1820                 /*
 1821                  * vtruncbuf() doesn't get the buffer overlapping the 
 1822                  * truncation point.  We may have a B_DELWRI and/or B_CACHE
 1823                  * buffer that now needs to be truncated.
 1824                  */
 1825                 error = vtruncbuf(vp, cred, td, nsize, biosize);
 1826                 lbn = nsize / biosize;
 1827                 bufsize = nsize & (biosize - 1);
 1828                 bp = nfs_getcacheblk(vp, lbn, bufsize, td);
 1829                 if (!bp)
 1830                         return EINTR;
 1831                 if (bp->b_dirtyoff > bp->b_bcount)
 1832                         bp->b_dirtyoff = bp->b_bcount;
 1833                 if (bp->b_dirtyend > bp->b_bcount)
 1834                         bp->b_dirtyend = bp->b_bcount;
 1835                 bp->b_flags |= B_RELBUF;  /* don't leave garbage around */
 1836                 brelse(bp);
 1837         } else {
 1838                 vnode_pager_setsize(vp, nsize);
 1839         }
 1840         return(error);
 1841 }
 1842 

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